Fuel injection nozzle

ABSTRACT

A fuel injection nozzle having a long narrow passage between the differential valve and the discharge orifices with narrow walls surrounding the passage to form a long narrow tip of small cross sectional area. The opening in the cylinder deck facing the combustion chamber receiving the tip is correspondingly small to decrease heat transfer from the combustion chamber to the needle valve.

United States Patent Inventor Alexander Dreisin Olymp'u 121$, Ill.

Appl. No. 882,120

Filed Dec. 4, 1969 Patented Oct. 12, 1971 Assignee Al1is-Chalmers Manufacturing Company Milwaukee, Wis.

FUEL INJECTION NOZZLE 10 Claims, 1 Drawing Fig.

US. Cl 123/32, 239/5 33 Int. Cl ..F02ln 61/14 Field ofSearch 123/32, 32

s'r, 32 VN, 32 F; 236/459, 95, 533

Primary ExaminerLaurence M. Goodridge Attorneys-Arthur L. Nelson, Robert B. Benson and Charles L. Schwab ABSTRACT: A fuel injection nozzle having a long narrow passage between the differential valve and the discharge orifices with narrow walls surrounding the passage to form a long narrow tip of small cross sectional area. The opening in the cylinder deck facing the combustion chamber receiving the tip is correspondingly small to decrease heat transfer from the combustion chamber to the needle valve.

awning? l 501 M Q M FUEL INJECTION NOZZLE This invention relates to a fuel injection nozzle for an internal combustion engine and more particularly to a fuel injection nozzle having a long sac passage in the nozzle tip defined by thin walls with the tip extending through a reduced diameter opening in the cylinder head facing the combustion chamber to substantially decrease heat transfer from combustion gases to needle valve seat.

Nozzle life of high output engines is often limited by excessive nozzle tip temperatures. The region of the nozzle orifices and sac holes, in other words the axial passage downstream from the valve seat of the needle valve can get as hot as 600 F., or even hotter. While high temperature steels are available, which retain their physical properties such as hardness and wear resistance at such elevated temperatures, the fuel oil trapped in the sac hole after the end of injection is subject to accelerated chemical changes, when the tip temperature exceeds 450, or at most 500 F. Fuel oil molecules crack leaving solid carbon deposits on the walls of the sac hole. As time goes on, carbon particles start a build up on the needle seat and, acting as an abrasive, lead to accelerated seat wear. As much as 80 percent of the total heat flow into the nozzle occurs across its projected tip area which faces the combustion chamber. During combustion, flame temperatures exceed 3,000 F. Heat flow into the nozzle occurs by means of convection and radiation.

In order to protect the seat area from high temperatures, attempts have been made in the past to position the needle seat farther up in the nonle body without materially affecting the cross sectional area exposed to the combustion gases. These attempts have not been successful because the longer sac hole tends to carbon up even faster than the conventional type nozzle with the shorter sac hole. This was due to the fact that the heat input into the nozzle was still the same inasmuch as the area exposed to the combustion chamber was unchanged. Further, the large cross-sectional area between the nozzle tip and the needle seat allowed unimpeded flow of heat due to the high temperatures that remained surrounding the whole length of the sac hole.

This invention proposes an improvement which will retain the long sac hole described above but whereby the walls surrounding the lower portion of sac hole were made thin and the heat flow from the combustion chamber is reduced. In addition, the opening in the cylinder deck facing the combustion chamber is reduced, decreasing substantially the nozzle area exposed to the heat of the flame. Accordingly, the thin walls of the sac holes and the reduced cylinder head opening which, in effect forms an annular lip protecting the nozzle tip from combustion heat, substantially reduces the heat transfer from the combustion gases to the needle valve seat.

It is an object of this invention to provide a fuel injection nozzle having along sac passage between the needle valve seat and the nozzle orifices.

It is another object of this invention to provide a fuel injection nozzle for an internal combustion engine having a long sac hole formed by the thin walls between the needle valve and the nozzle orifices with reduced cylindrical head opening for reducing heat transfer from the combustion chamber to the needle valve seat.

It is a further object of this invention to provide a fuel injection nozzle having a long sac hole with thin walls positioned in a cylinder head forming reduced cross-sectional area opening to limit the heat transfer coming from the combustion chamber and transferred to the needle valve seat and thereby reduce temperatures of the needle valve seat to prevent carbon depositing on the needle valve seat.

The objects of this invention are accomplished by providing a nozzle having along thin walled sac passage extending from the differential valve to the nozzle tip. The nozzle forms a reduced outline at the tip end as compared to the main body of the nozzle. A reduced diameter opening in the engine head permits the nozzle tip to extend into the combustion chamber through a small cross-sectional area. The shielding by the engine head of a substantial portion of the body of the injection nozzle and permitting only the small tip area to exposure by the hot combustion gases in the combustion chamber limits the heat transfer from the combustion gases to the needle valve seat. These features substantially reduce the temperatures of the needle valve seat and the fluid retained in the inlet passages surrounding the needle valve seat. The breakdown of fuel depositing carbon on the needle valve seat is substantially eliminated by the cooler operating temperatures.

Referring to the drawings, a preferred embodiment of this invention is illustrated.

The drawings illustrate a cross section of a diesel engine cylinder and fuel injector. The block 1 receives the sleeve 2 upon which the head 3 is mounted. The piston 4 reciprocates within the sleeve 2 and defines a plurality of annular recesses on its external periphery receiving a plurality of piston rings. The recess in the end of piston 4 forms a portion of the combustion chamber 5. The fuel injector extends into the combustion chamber for intennittently injecting fuel into the combustion chamber when the engine is operating.

The head 3 also supports a valve 6 engaging the valve seat 7 for controlling a flow of gas through the passage 8.

The injector 9 is mounted centrally above the piston 4 and the tip 10 having orifices l1 inject fuel into the combustion chamber. The fuel injector 9 forms a body 12 carrying'the needle 13 forming a needle valve with the seat 14. The needle 13 is biased to a closed position by a spring 15 which is compressed between a spring retainer on spindle rod 16 engaging the end of the needle 13, and the washer 17. The washer 17 is positioned on the end of the adjusting screw 18 which can be adjusted by means of a suitable wrench inserted in the opening 19 of the cover 20. The sleeve 21 is received within the cover 20 in the body 12 and is threadedly fastened together with the spacer 22 and washers 23 and 24 to form the upper assembly of the fuel injection nozzle. The upper end of the fuel injection nozzle provides for adjustment of the compression force of the spring 15 biasing the needle 13 of the needle valve closed. The conduit 25 defines an inlet passage 26 feeding into the body 12 of the fuel injector 9. The inlet passage 26 feeds downwardly into the chamber 27 surrounding the needle valve in the lower portion of the body 12. With an increase in pressure in the inlet passage 26 and the chamber 27, the needle valve will be biased to an open position for fuel injection. The air space 47 surrounding the injector 9 between the needle valve 33 of the injector 9 and the combustion chamber 5 also acts as a heat barrier.

The fuel injector 9 is fastened to the head by suitable means on the body 12 to maintain the base sleeve 28 of the fuel injector firmly seated on the sealing washer 29 at the base of the opening 30 receiving the sleeve 31. The chamber 27 is in communication with an annular chamber32 surrounding the needle 13. The increased pressure in the chamber 27 operates against the surface 34 for opening the needle valve.

The tip 10 extends downwardly from the seat 14 and is formed by thin walls 38 defining the long sac passage 39 which is in communication with the orifices 11. The cylinder head 3 defines a mating opening 40 to receive the tip 10. The tip 10 extends through the opening 40 into the combustion chamber 5 with only a limited area of the tip exposed to the combustion gas in the combustion chamber 5. The timing and quantity of injection into the combustion chamber is controlled by a fuel injection pump not shown and may be conventional in its operation.

The fuel injection nozzle as shown employs a needle valve 33 which operates in response to increasing the pressure in the inlet passage 26 and chamber 27. The pressure opens the needle valve for fuel injection. The needle valve seat temperatures are substantially reduced by the reduction of the exposed area of the fuel injector tip 10. The cylinder head 3 in effect forms an annular heat-protecting flange 45 which defines the opening 40 which receives the tip 10. The orifices 11 in the tip extend into the combustion chamber and expose a very small portion of the nozzle to the hot gases in the combustion chamber 5.

The flange 45 of the head 3 operating as a heat shield provides a barrier for heat transfer from the combustion chamber 5 to the nozzle 9. The opening 35 in communication with the opening 40 is enlarged to receive the larger portion defining the valve seat 14. The temperature of the fuel in annular chamber 32 surrounding the needle 13 is maintained at a substantially lower temperature than conventional fuel injection nozzles and accordingly the breakdown of fuel producing by excessive heat causing carbon deposits on the valve seat 14 are substantially eliminated.

The preferred embodiment of this invention has been illustrated and described.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A fuel injection nozzle in an internal combustion engine comprising, means defining a body of the fuel injection nozzle having inlet passage means, a needle valve connected to said inlet passage means for opening in response to a predetermined pressure of a pressurized fluid in said inlet passage means, a nozzle tip defining orifice means for discharging pressurized fluid into a combustion chamber, long thin walls connecting said needle valve to said nozzle tip defining a long sac passage connected to the orifice means and a substantially reduced cross-sectional area of the nozzle between said needle valve and said nozzle tip relative to said body, a cylinder head defining an opening for receiving the body of said fuel injector, said cylinder head defining an annular fiange of a thickness substantially equal to the length of said long sac passage and forming a continuation of said opening of substantially reduced diameter surrounding the tip of said fuel injector and forming an air space between the nozzle and head from the needle valve to the combustion chamber, said head and mounting of said nozzle providing a heat shield and insulation means to reduce heat transfer from hot combustion gases in a combustion chamber to the needle valve in said fuel injector for providing cool operating temperatures for said needle valve.

2. A fuel injection nozzle in an internal combustion engine as set forth in claim 1 wherein said thin walls of said nozzle define a thickness no greater than the diameter of said long sac passage and are intermittently cooled during each cycle of fuel injection.

3. A fuel injection nozzle in an internal combustion engine as set forth in claim 1 wherein the body of said nozzle defines a tapered portion adjoining the long thin walls connected to said needle valve whereby the tip of said fuel injector is of substantially smaller cross-sectional area than the body of said fuel injector.

4. A fuel injection nozzle in an internal combustion engine as set forth in claim 1 wherein said thin walls of said fuel injection nozzle define a cross-sectional area of approximately oneninth 0f the cross-sectional area of the body of said nozzle to reduce heat flow to said needle valve.

5. A fuel injection nozzle in an internal combustion engine as set forth in claim 1 wherein said thin walls defining said long sac passage form an external diameter no greater than the external diameter of the needle in said needle valve for limiting the heat transfer to the needle valve of said nozzle.

6. A fuel injection nozzle in an internal combustion engine as set forth in claim 1 wherein said head defines an annular heat shield of substantial thickness forming the opening for receiving the fuel injection nozzle tip.

7. A fuel injection nozzle in an internal combustion engine as set forth in claim 1 wherein said nozzle includes a sealing washer positioned intermediate the body of said fuel injection nozzle and said head to reduce heat flow toward said nozzle body.

8. A fuel injection nozzle in an internal combustion engine as set forth in claim 1 wherein said tip defines a cross-sectional diameter of less than one-third of the length of said long sac passage in said nozzle tip to reduce heat flow toward said nozzle body. v

Q A fuel injection nozzle in an internal combustion engine 

1. A fuel injection nozzle in an internal combustion engine comprising, means defining a body of the fuel injection nozzle having inlet passage means, a needle valve connected to said inlet passage means for opening in response to a predetermined pressure of a pressurized fluid in said inlet passage means, a nozzle tip defining orifice means for discharging pressurized fluid into a combustion chamber, long thin walls connecting said needle valve to said nozzle tip defining a long sac passage connected to the orifice means and a substantially reduced crosssectional area of the nozzle between said needle valve and said nozzle tip relative to said body, a cylinder head defining an opening for receiving the body of said fuel injector, said cylinder head defining an annular flange of a thickness substantially equal to the length of said long sac passage and forming a continuation of said opening of substantially reduced diameter surrounding the tip of said fuel injector and forming an air space between the nozzle and head from the needle valve to the combustion chamber, said head and mounting of said nozzle providing a heat shield and insulation means to reduce heat transfer from hot combustion gases in a combustion chamber to the needle valve in said fuel injector for providing cool operating temperatures for said needle valve.
 2. A fuel injection nozzle in an internal combustion engine as set forth in claim 1 wherein said thin walls of said nozzle define a thickness no greater than the diameter of said long sac passage and are intermittently cooled during each cycle of fuel injection.
 3. A fuel injection nozzle in an internal combustion engine as Set forth in claim 1 wherein the body of said nozzle defines a tapered portion adjoining the long thin walls connected to said needle valve whereby the tip of said fuel injector is of substantially smaller cross-sectional area than the body of said fuel injector.
 4. A fuel injection nozzle in an internal combustion engine as set forth in claim 1 wherein said thin walls of said fuel injection nozzle define a cross-sectional area of approximately one-ninth of the cross-sectional area of the body of said nozzle to reduce heat flow to said needle valve.
 5. A fuel injection nozzle in an internal combustion engine as set forth in claim 1 wherein said thin walls defining said long sac passage form an external diameter no greater than the external diameter of the needle in said needle valve for limiting the heat transfer to the needle valve of said nozzle.
 6. A fuel injection nozzle in an internal combustion engine as set forth in claim 1 wherein said head defines an annular heat shield of substantial thickness forming the opening for receiving the fuel injection nozzle tip.
 7. A fuel injection nozzle in an internal combustion engine as set forth in claim 1 wherein said nozzle includes a sealing washer positioned intermediate the body of said fuel injection nozzle and said head to reduce heat flow toward said nozzle body.
 8. A fuel injection nozzle in an internal combustion engine as set forth in claim 1 wherein said tip defines a cross-sectional diameter of less than one-third of the length of said long sac passage in said nozzle tip to reduce heat flow toward said nozzle body.
 9. A fuel injection nozzle in an internal combustion engine as set forth in claim 1 wherein said head defines an annular heat shield forming a heat sink for absorbing heat from the hot combustion gases to prevent transfer of heat to the needle valve.
 10. A fuel injection nozzle in an internal combustion engine as set forth in claim 1 including said tip defining an exposed area adapted for facing hot gases in an internal combustion engine equal to the cross sectional area of the long sac passage walls to thereby limit heat transfer to the needle valve seat. 